Refrigerating system



REFRIGERATING SYSTEM Filed Aug. 28, 1940 inventor Alwim B. Nzwtomattorney Patented Dec. 8, 1942 BEFRIGERATING SYSTEM Alwin B. Newton,Minneapolis, Minn., alsignor to Minneapolis-Honey well RegulatorCompany,

Minneapolis, Minn., a corporation of Delaware Application August 28,1940, Serial No. 354,516 9 claims. (01. 62-8) My invention relatesto-refrigerting systems, particularly those of the type wherein gasisliquefled in acondenser and then expanded in an evaporator. It has beencommon practice inthe past to control the supply of refrigerant to theevaporator in accordance 'with the accumulation of liquid in thecondenser by the use of a socalled high side float valve. My inventionis concerned with improved methods and means of controlling the supplyof refrigerant'to the evaporator in eifect in accordance with theaccumulation of liquid in th condenser.

An object of my invention is to provide a pressure operated expansion ofthe above mentioned type, the pressure for valve for use in systems Loperating the valve being controlled by a pilotvalve responsive ineflect to the accumulation of liquid in the condenser.

Another object of my invention is to control the release of liquid fromacondenser in effect in accordance with the accumulation of liquidtherein by adjusting a release valve dependently upon the differencebetween the temperature of condensing refrigerant and the temperature ofliquid collected in the lower partlgf the condenser. The liquidcollected in the lower part of the condenser is subcooled below thetemperature of the refrigerant condensing in the upper part of thecondenser and as the liquidv collects in the condenser the dilferencebetween the temperature of the liquid at the lower part and thetemperature of condensing refrigerant higher up in the condenser becomesgreater. Thus by controlling .the release of liquid from the condenserin accordance with this temperature difference, the use of a high sidefloat may be dispensed with even though equivalent results are produced.

Another object is to provide a pressure operated expansion valve for arefrigerating system of the-type mentioned controlled by a pilot valveresponsiveto the difference between the temperature of liquid collectedin the condenser and'the temperature of condensing refrigerant wherebythe expansion valve is controlled in effect in accordance with theaccumulation of liquid in thecondenser without the use of a high sidefloat. Incarrying out this object, it is a further object of myinvention to convey gas from the condenser for operating the expansionvalve and pass it in heat exchange relationship with a temperatureresponsive element controlling the pilot valve.

Further 'objects and advantages of the invention will become apparentfrom the following detailed description and annexed drawing wherein thesingle figure of the drawing represents a corn- .driven by an eiectricmotor l2. The discharge of the compressor is connected pression typerefrigerating system embodying my invention. 7

Referring to the drawing, I have shown a reirigerating system comprisinga compressor III II by meansof a belt to a condenser ii of the coil typeby a pipe I. The condenser has a receiver I4 in which liquid refrigerantcollects, the receiver being connected to an expansion valve II by l8.ofthe pipe connecting pansion valve being shown enlarged. The outlet oi'the expansion valve I6 is connectedto an evaporator 33 by a pipe l9 andthe outlet of (the evaporator 33 is connected to the suction side of thecompressor by a pipe 20.

The compressor motor ll controller 36.

a pipe H, a portion the receiver and ex- Ihe controllerjfi is the sameas that disclosed in detail in the application of Albert L. Judson andCarl G. Kronmiller Serial No. 196,447, filed March 17, 1938. Thecontroller 36 includes elements responsive to the compressor suction anddischarge pressures, the elements being connected to the suction pipe 20and d ischarge pipe l6 by tubes 31 and 38, respectively. The controllerembodies switching mechanism operated by the pressure responsiveelements whereby the motor ll wires 39, 40 and 4|. in response to thecontroller 36 is to start the is controlled through the compressor at arelatively high suction pressure and to stop it at a relatively lowsuction pressure. The-compressor may also be stopped at any time in theevent that the discharge pressure rises to an unduly high value. v I

Numeral 2| designates the body of the expansion valve IE. it having aninlet 22 and an outlet 23. The upper part of the valve body is closed bya plate member 24 and superimposed upon the plate member 24 is a casing25, the valve*"'body, plate 24 and casing 25 being secured together inany suitable manner so as to make the engaging parts fluid tight. Theoutlet 23 forms a valve seat which is adapted to be engaged by a valvehead 26 to which is attached a stem 21 which extends through an openingin the plate 24 and into the interior of the casing 25. Disposed withinthe casing 25 is a pressure responsive device pansible and contractiblecells 29 and 30 each of which is'made up of two complementary diaphragmssealed together at their edges. The

28 comprising two excells 29 and 30 are spaced by a spacing ring 3| andthe device 28 by a similar ring is controlled by a r The operation ofthe system is spaced from the plate 24 '32.. Within the cell 29 is aring member 34,

, disc 59.

the tube and pipe l1.

ring member 33 and within the cell 3|] is a similar these ring membershaving suihcient'thickness to prevent complete collapse of the cellswhereby the diaphragms might be damaged. The valve stem 21 extendswithin the cells 29 and 30 and at its upper end carries a disc 42 whichis suitably secured to the upper diaphragm of the upper cell. Numeral 43designates a coil spring which encircles the valve stem 21, one end ofthe spring bearing against the plate 24 and the other end bearingagainst disc 42 adjacent the upper diaphragm of cell 26 so that thespring tends to expand the device direction. Nu-

28 urging the valve in opening meral 44 designates a seal-off bellowsconnected to the valve member 26 and the plate 24 to seal the interiorof the valve body from the interior of the expansible cellsr There is alongitudinal orifice 45in the valve stem 21 and valve member 26, thisorifice being coaxial with a similar orifice in disc 42 and in the upperdiaphragm of cell 29 whereby communication is provided between the spacewithin the casing 25 exterior of the device 26 and the outlet side ofthe valve. The casing 25 is adapted to contain a pressure and the device28 expands and'contracts depending upon the magnitude of this pressureand adjusts the position of the valve member 26 with respect to its seataccordingly.

Numeral 56 designates generally a temperature responsive pilot valvemechanism which controls the pressure applied to the pressure operatedvalve 5. The mechanism 56 comprises a tube 5| having an annular detent52 near one end which retains in its proper place an end plug 56. Anadjustable screw 54 extends through the end plug 53, the inner end ofthe screw 54 being slotted so as to receive the end of a coiled bimetalelement 55. The screw 54 has a shoulder 56 and between this shoulder andthe plug 53 is a fibre washer or disc to prevent the escape of pressurearound the screw 54. The screw 54 may be locked in any adjusted positionby means of a lock nut 51. The other end of the tube 5| has a similarannular detent 58 in engagement with which is a disc 59. The oppositeend of the bimetal element 55 is engaged in a slot in a pin 60 whichextends through the disc 59. Numeral 6| designates a second tube similarto the tube 5| but of slightly smaller diameter, the tube 6| beingtelescoped within the tube 5| and having its endbearing against theclosed by a plug 62 which has a bore 63 and a screw threaded counterbore 64. The counter bore 64 receives a screw plug 65 which carries 1 'avalve head 66 adapted to seat on the seat formed by the counter bore.The screw plug 65 has a groove 61 along its side so that. fluid leavingthe interior of the tube 6| through the bore 63 may pass the valve andthe screw plug. The left end of the screw plug 65 is slotted andreceives the end of a coiled bimetal element 68 similar to the element55, the other end of the element 68 being receivedin a slot in theopposite end of the pin 60. 'The end plug 62 has another bore 69 wherebyfluid may be admitted to the tube 6|. 3

The tube 5| which is of larger diameter is in intimate thermal contactwith the portion l8 of the pipe connecting the condenser and expansionvalve as will be seen, the device 50 beingheld in place by a clamp orstrap 12 passing around 55 is therefore responsive to the temperature ofThe bimetal element through the' tube the refrigerant in the pipeconnecting the condenser and the expansion valve. The tube 6| beingspaced from the pipe portion IS, the bimetal element 68 is notresponsive to the temperature of the refrigerant passing from thecondenser to the expansion valve but it is .responsive to thetemperature of fluid within the tube 6|.

The bore 69 may be connected to one of the condenser coils, that is, apoint on the condenser near the upper part thereof by a tube 13. Thebore 63 is connected to the casing 25 by a tube 14. The tube 13 isconnected to a point on the condenser yet condensed such that gas may beconveyed 13 to the interior of the tube 6| where the gas condenses andthence. through the tube 14 to the casing 25. The bimetal element 68 istherefore responsive to the temperature of the condensing refrigerantwhile the bimetal element 55 is responsive to thetemperature of thecondensed refrigerant, that is, liquified refrigerant which collects inthe receiver M. The bimetal elements 55 and 68 are arranged to act inopposition, that is, if both are afiected by anincrease in temperatureone of them will tend to move the valve member 66 away from its seat andthe other will tend to move it towards itsseat, the valve member 66 ofcourse being moved toward or away from its seat by reason of the screwplug 65 being turned when the bimetal elements expand or contract.

The temperature of the refrigerant Which' be connected to the top ofcondenser 03 so asto take off superheated rather than saturated gas,

the length of the tube insuring that the gas condenses upon reachingtube 6| so that the temperature therein will correspond to condens- Theopposite end of the tube 6|! is ing pressure in the condenser. in thereceiver M will of course be substantially The pressure the same as thecondensing pressure higher up in the coil. However the temperature ofthe liquid refrigerant in the receiver it will not correspond to thepressure existing in the condenser, that is, the condensing pressure,because after the refrigerant condenses and flows downwardly through thecoil it is subcooled by the air passing over the condenser coil andinasmuch as after.

having been condensed there is no further heat of condensation, thetemperature of the liquid refrigerant is lower than the temperature ofthe gas in tube I3. Thus the more liquid there is in the receiver andthe condenser the greater difference there may be between thetemperature of the liquid in the receiver and the temperature of thecondensing gas. Inasmuch as the, bimetal elements 55 and 68 act inopposition as described above when they are subjected to differingtemperatures the pilot valve mechanism will be actuated dependently uponthe amount of the difference. When no refrigerant has been condensed inthe condenser and only high pressure gas is present therein, the pilotvalve will be wide open and high pressure gas will be communicated fromthe upper part of the condenser through the tube 13, the pilot valve andthe tube 14 to the casing 25 and this pressure acting on the pressureoperated device 28 will maintain the expansion valve l5 in closedposition. As liquid collects in the receiver l4 due to condensation, thetemperatures affecting the bimetal elements 55 and 68 will diverge asdescribed above. In

l3 wherein' the refrigerant has not expands tending to move memberaccordance with the accordance with this divergence in temperatures thepilot valve, that is, the member 66 will gradually move toward its-seattending to throttle the gas flow from the upper part of the condenser tothe interior of the casing 25. As this flow of gas is throttled thepressure within the casing 25 is reduced, it being understood that theorifice 45 which is restricted permits the accumulated gas within thecasing 25 to bleed off to the outlet side of valve l5. As the L pressurewithin the casing 25 isthus reduced the device 28 26 away from its seatthus opening the valve. Thus the pressure in casing 25 and the positionof the expanslon valve I is controlled in accordance with the'difference between the temperatures affecting the bimetal elements 55and 68. The supply of refrigerant to the evaporator, that is, therelease of liquid refrigerant from the condenser is therefore controlledin effect in accordance with the accumulation of liquid refrigerant inthe condenser and receiver.

The position of the valve member 66 may be means for the valvecomprising a first device 'responsive to temperature of liquefiedrefrigerant at the lower part of the condenser and a second deviceresponsive to temperature of condensing refrigerant, said two deviceswhereby said valve is positioned dependently upon the difference betweensaid temperatures.

4. In a refrigerating system of the type having refrigerant condensingmeans and an evaporator, means comprising a valve for controlling thesupply of refrigerant to the evaporator, control means for the'valvecomprising a first device conveniently manually adjusted by adjustingscrew 54 whereby the amount of liquid maintained in the condenser can beadjusted.

From the foregoing those skilled in the art will appreciate that myinvention makes possible the attainment of results equivalent to thoseattained when a high side float type expansion valve is used. With myparticular arrangement the expansion valve itself can be placed in anydesired location, it not being necessary as in the case of a floattoplace itwhere the liquid refrigerant accumulates. The pilot valvemechanism may be made very small and may be produced very inexpensivelyand by reason of the particular bleed circuit arrangement only a singleconnection to the main expansion valve is required.

The embodiment of my invention which I have,

disclosedis exemplary of forms which it may take and of modificationswhich may be made in it. My disclosure is intended to be illustrativeonly and the boundaries of my invention are to be determined therefore,not in accordance with v the disclosure but only in accordance with thescope'of the appended claims.

I claim as my invention:

1. In a refrigerating system of the type having acondenser forliquefying gas, and an evaporator, in combination, means comprising amain I valve for controlling the supply of refrigerant to theevaporator,

pressure responsive means for adjusting said main valve, means forcommunicating refrigerant from said condenser to said pressureresponsive means foroperating the main valve, a pilot valve controllingthe pressure in said pressure responsive means, and control meansresponsive in effect to the accumulation of liquid in said condensercontrolling saidpilot valve whereby said main valve is controlled ineffect in accumulation of liquid in the condenser, said control meanscomprising an element responsive to the temperature of liquidrefrigerant at the lower part of the condenser and an element responsiveto the temperature of con-- densing refrigerant, said elements being sorelated as to position said pilot valve dependently upon the differencebetween said temperatures.

2. In a refrigerating system of the type having refrigerant condensingmeans and an evaporator, a valve for controlling/the supply ofrefrigerant to the evaporator, means responsive to temperature ofliquefied refrigerant at the lower part ofthe condenser, meansresponsive to the temperaresponsive to temperature of liquefiedrefrigerant at the lower part of the condenser and a second deviceresponsive to temperature of condensing refrigerant, said'twodevicesacting in opposition whereby said valve is positioned dependently uponthe differenceibetween said temperatures, said control means including apressure operated element and means whereby'the pressure for actuatingby said devices.

5. In a refrigerating system of the type having refrigerant condensingmeans and an evaporator, a valve for controlling the-supply ofrefrigerant to the evaporator, means responsive to temperature ofliquefied refrigerant at the lower part of the condenser, meansresponsive to the temperature of condensing refrigerant and operatingmeans for the valve controlled jointly by both of .the aforementionedtemperature responsive means whereby the valve is positioned dependentlyupon the difference between said temperatures, said temperatureresponsive means comprising bimetal elements, one being disposed in heatexchange relationship with liquefied refrigerant and the otheif' havingmeans associated therewith whereby refrigerant is conveyed from thecondenser andpassed in contact with it.

6. In a refrigerating system of the compression type having acompressor, a condenser, and an expander, in combination a pressureoperated expansion valve having a pressure chamber, means communicatingrefrigerant from the high side of the system to said chamberfor'operating the valve, a pilot valve controlling the pressure in saidchamber, and means responsive in effect to the accumulation ofrefrigerant condensed in the condenser controlling said pilot valve,said last means comprising an element responsive to the temperature ofcondensed refrigerant and an element responsive to the temperature ofcondensing refrigerant, said elements being so related as to adjust saidpilot valve dependently upon the difference between said temperatures.

7. In a'refrigerating system of the compression type having acompressor, a condenser, and an expander, incombination, a pressureoperated expansion valve having a pressure chamber, means communicatingrefrigerant from the high side of the system to said chamber foroperating the valve. a pilot valve controlling the pressure in 'saidchamber, and means responsive in effect to the accumulation ofrefrigerant condensed in the condenser controlling said pilot valve,said acting in opposition said element is controlled 1 last meanscomprising a first element responsive to the temperature of condensedrefrigerant and a' second element responsive to the temperature ofcondensing refrigerant, said elements being so related as to adjust saidpilot valve dependently upon thedifference betweensaid temperatures,said refrigerant communicating means including means for passing saidrefrigerant from the high side in heat exchange relationship with saidsec.- ond temperature responsive element.

8. In a refrigerating system of the type having refrigerant condensingmeans and an evaporator, a valve for controlling the supply ofrefrigerant to the evaporator, pressure responsive means for positioningsaid valve, means conveying gas from the condenser to said pressureresponsive means, a first device responsive to the temperature of theliquefied refrigerant at the lower part. of the condenser, a seconddevice responsive to the temperature of the condensing refrigerant, saiddevices being connected in opposition, and-means operated by saiddevices for varying the pressure of the gas delivered to said pressureresponsive means whereby said valve is positioned in'accordance with thedifference peratures.

. 9. In a refrigerating system of the type having refrigerant condensingmeans and an evaporator, means comprising a valve for controlling thesupply of refrigerant to the evaporator, control means for the valvecomprising a first device responsive to temperature ofliquefiedmefrigerant at the lower part of the condenser and a seconddevice responsive to temperature of condensing refrigerant, said twodevices acting in opposition, said control means also including apressure operated element, means for conveying gas from said condenserto said element for operating said element, and a valve in saidconveying means, said devices operating said last mentioned valve forcontrolling the flow of said gas to said element whereby said firstmentioned valve is positioned dependently upon the difference betweenthe temperatures to which the two devices respond.

" ALWIN B. NEWTON.

between said two tem-

